Fault　characteristics　analysis　is　precondition　of　relay　protection.　Theoretical　derivation　of　permanent　magnet　synchronous　generator　(PMSG)　fault　current　is　necessary.　In　accordance　with　the　theory　that　grid-side　converter　of　PMSG　is　a　power　balance　system　under　control　action,　an　electromagnetic　transient　model　of　PMSG　was　proposed.　Based　on　it,　the　active　and　reactive　current　was　deduced　and　then　the　expression　of　three-phase　fault　current　was　obtained　and　its　components,　frequency,　and　attenuation　speed　of　every　component　and　other　characteristics　were　analysed　comprehensively.　Simulation　on　PSCAD　and　field　fault　recording　data　as　practical　analysis　verifies　that　the　expressions　and　the　characteristics　are　correct.　The　results　of　this　paper　are　not　only　important　to　relay　protection,　but　also　are　references　to　transient　calculation　and　transient　modelling.　©　Institution　of　Engineering　and　Technology.　All　rights　reserved.